<ownershipDocument><schemaVersion>X0201</schemaVersion>    <documentType>4</documentType><periodOfReport>2004-01-02</periodOfReport><notSubjectToSection16>0</notSubjectToSection16><issuer><issuerCik>0000230557</issuerCik><issuerName>SELECTIVE INSURANCE GROUP INC</issuerName>        <issuerTradingSymbol>SIGI</issuerTradingSymbol></issuer><reportingOwner><reportingOwnerId><rptOwnerCik>0001036310</rptOwnerCik><rptOwnerName>KEARNS WILLIAM M JR</rptOwnerName></reportingOwnerId><reportingOwnerAddress><rptOwnerStreet1>40 WANTAGE AVENUE</rptOwnerStreet1><rptOwnerStreet2></rptOwnerStreet2><rptOwnerCity>BRANCHVILLE</rptOwnerCity><rptOwnerState>NJ</rptOwnerState><rptOwnerZipCode>07890</rptOwnerZipCode><rptOwnerStateDescription></rptOwnerStateDescription></reportingOwnerAddress><reportingOwnerRelationship><isDirector>1</isDirector><isOfficer>0</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther><officerTitle></officerTitle><otherText></otherText></reportingOwnerRelationship></reportingOwner><nonDerivativeTable><nonDerivativeTransaction><securityTitle><value>Common Stock</value></securityTitle><transactionDate><value>2004-01-02</value></transactionDate><deemedExecutionDate></deemedExecutionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>A</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionTimeliness><value></value></transactionTimeliness><transactionAmounts><transactionShares><value>335</value></transactionShares><transactionPricePerShare><value>32.15</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>79595</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value></value></natureOfOwnership></ownershipNature></nonDerivativeTransaction></nonDerivativeTable><derivativeTable></derivativeTable><footnotes></footnotes><ownerSignature><signatureName>William M Kearns, Jr.</signatureName><signatureDate>2004-01-06</signatureDate></ownerSignature></ownershipDocument>

